The present invention relates to a process for preparing .DELTA..sup.9(11) - and/or .DELTA..sup.16 -unsaturated steroids.
As is known, .DELTA..sup.9(11) -unsaturated steroids can be prepared from the corresponding 11.beta.- or .alpha.-alcohols by conversion into the sulfonates (e.g. mesylates) and elimination of these esters under alkaline conditions (P. Wieland et al., Helv. 43: 523 [1960]), or, after blocking the carbonyl groups, with phosphorus oxychloride in pyridine (S. Bernstein et al., JACS 75: 4830 [1953]).
It is furthermore known that .DELTA..sup.16 -unsaturated steroids of the pregnane series can be obtained from the corresponding 17.alpha.-hydroxy-20-ketopregnanes by treatment with phosphorus oxychloride in pyridine at room temperature (Fried & Edwards, Organic Reactions in Steroid Chemistry, II: 171 [1972]).
These conventional chemical methods, however, are disadvantageous in that they either proceed by way of several stages or provide unsatisfactory yields.